The antimetastatic therapy is a new field of chemotherapy of tumors and is very promising, since it opens wide opportunites for surgical intervention, inhibiting or even eliminating the origination of metastases (secondary tumors) after the removal of the primary tumor. It is known (British Medical Journal, vol. 1, No. 5800, 1972, A. W. Le Serve, K. Hellmann "Metastases and the Normalization of Tumor Blood Vessels by YCRF-159: A Nero Type of Drug Action", pp. 597-601; European Journal of Cancer, vol. 11, No. 3, 1975, A. Atlierfon "The Effect of (.+-.) 1,2-bis(3,5-dioxopiperazin-1-yl)propane (JCRF-159) on Liver Metastases from a Hamster Lymphoma", 383-388) that the antitumor preparation JCFR-159 (Razzoxane; synthesized by Imperial Cancer Research Fund) (.+-.) 1,2-bis(3,5-dioxopiperazin-1-yl)propane has a certain antimetastic activity, but this preparation is somewhat toxic (LD.sub.50 1,000 mg/kg) and side effects (causes leucopenia, thrombocytopenia and dyspeptic phenomena) European Journal of Cancer, vol. 13, No. 8, R. E. Bellet, M. Rozenzweigh, D. D. Van Hoff, J. S. Penta, T. H. Wassermann, F. M. Muggia "JCRF-159: Current Status and Clinical Prospects", pp. 1293-1298.